Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices may include clutches and at least one brake.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/912,757 filed on Apr. 19, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingeight or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches and brakes.

An embodiment of the transmission includes an input member, an outputmember, first, second, third and fourth planetary gear sets each havingfirst, second and third members, a first interconnecting membercontinuously interconnecting the first member of the first planetarygear set with a stationary element, a second interconnecting membercontinuously interconnecting the second member of the first planetarygear set with the third member of the third planetary gear set, a thirdinterconnecting member continuously interconnecting the third member ofthe first planetary gear set with the second member of the secondplanetary gear set, a fourth interconnecting member continuouslyinterconnecting the first member of the second planetary gear set withthe first member of the third planetary gear set, a fifthinterconnecting member continuously interconnecting the second member ofthe third planetary gear set with the third member of the fourthplanetary gear set. Five torque transmitting mechanisms are selectivelyengageable to interconnect one of the first, second, and third memberswith another of the first, second, third members, and the stationaryelement. The torque transmitting mechanisms are selectively engageablein combinations of at least two to establish at least eight forwardspeed ratios and at least one reverse speed ratio between the inputmember and the output member.

In one aspect of the present invention, a first of the five torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the first planetary gear set with the third member ofthe second planetary gear set.

In another aspect of the present invention, a second of the five torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the first planetary gear set with the stationaryelement.

In yet another aspect of the present invention, a third of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe third member of the second planetary gear set with at least one ofthe first member of the fourth planetary gear set and the input member.

In yet another aspect of the present invention, a fourth of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe third member of the second planetary gear set with the second memberof the fourth planetary gear set.

In yet another aspect of the present invention, a fifth of the fivetorque transmitting mechanisms is selectively engageable to interconnectat least one of the first member of the second planetary gear set andthe first member of the third planetary gear set with the second memberof the fourth planetary gear set.

In yet another aspect of the present invention, the first members aresun gears, the second members are carrier members, and the third membersare ring gears.

In yet another aspect of the present invention, the input member iscontinuously interconnected with the first member of the fourthplanetary gear set and the output member is continuously interconnectedwith the second member of the fourth planetary gear set.

In yet another aspect of the present invention, one of the torquetransmitting mechanisms is a brake and four of the torque transmittingmechanisms are clutches.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Another embodiment of the transmission of the present invention includesan input member, an output member, first, second, third and fourthplanetary gear sets each having first, second and third members, whereinthe input member is continuously interconnected with the first member ofthe fourth planetary gear set and the output member is continuouslyinterconnected with the second member of the fourth planetary gear set,a first interconnecting member continuously interconnecting the firstmember of the first planetary gear set with a stationary element, asecond interconnecting member continuously interconnecting the secondmember of the first planetary gear set with the third member of thethird planetary gear set, a third interconnecting member continuouslyinterconnecting the third member of the first planetary gear set withthe second member of the second planetary gear set, a fourthinterconnecting member continuously interconnecting the first member ofthe second planetary gear set with the first member of the thirdplanetary gear set, a fifth interconnecting member continuouslyinterconnecting the second member of the third planetary gear set withthe third member of the fourth planetary gear set. A first torquetransmitting mechanism is selectively engageable to interconnect thesecond member of the first planetary gear set with the third member ofthe second planetary gear set. A second torque transmitting mechanism isselectively engageable to interconnect the second member of the firstplanetary gear set with the stationary element. A third torquetransmitting mechanism is selectively engageable to interconnect thethird member of the second planetary gear set with at least one of thefirst member of the fourth planetary gear set and the input member. Afourth torque transmitting mechanism is selectively engageable tointerconnect the third member of the second planetary gear set with thesecond member of the fourth planetary gear set. A fifth torquetransmitting mechanism selectively engageable to interconnect the atleast one of the first member of the second planetary gear set and thefirst member of the third planetary gear set with the second member ofthe fourth planetary gear set. The torque transmitting mechanisms areselectively engageable in combinations of at least two to establish atleast eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.

In one aspect of the present invention, the first members are sun gears,the second members are carrier members, and the third members are ringgears.

In another aspect of the present invention, the stationary element is atransmission housing.

Another embodiment of the transmission of the present inventionincluding an input member, an output member, a first, second, third andfourth planetary gear sets each having a sun gear, a carrier member anda ring gear, wherein the input member is continuously interconnectedwith the sun gear of the fourth planetary gear set and wherein theoutput member is continuously interconnected with the carrier member ofthe fourth planetary gear set, a first interconnecting membercontinuously interconnecting the sun gear of the first planetary gearset with a stationary element, a second interconnecting membercontinuously interconnecting the carrier member of the first planetarygear set with the ring gear of the third planetary gear set, a thirdinterconnecting member continuously interconnecting the ring gear of thefirst planetary gear set with the carrier member of the second planetarygear set, a fourth interconnecting member continuously interconnectingthe sun gear of the second planetary gear set with the sun gear of thethird planetary gear set, a fifth interconnecting member continuouslyinterconnecting the carrier member of the third planetary gear set withthe ring gear of the fourth planetary gear set. A first torquetransmitting mechanism is selectively engageable to interconnect thecarrier member of the first planetary gear set with the ring gear of thesecond planetary gear set. A second torque transmitting mechanism isselectively engageable to interconnect the carrier member of the firstplanetary gear set with the stationary element. A third torquetransmitting mechanism is selectively engageable to interconnect thering gear of the second planetary gear set with at least one of the sungear of the fourth planetary gear set and the input member. A fourthtorque transmitting mechanism is selectively engageable to interconnectthe ring gear of the second planetary gear set with the carrier memberof the fourth planetary gear set. A fifth torque transmitting mechanismis selectively engageable to interconnect at least one of the sun gearof the second planetary gear set and the sun gear of the third planetarygear set with the carrier member of the fourth planetary gear set. Thetorque transmitting mechanisms are selectively engageable incombinations of at least two to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.

In one aspect of the present invention, the stationary element is atransmission housing.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way;

FIG. 1 is a lever diagram of an embodiment of an eight speedtransmission according to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of an eight speedtransmission according to the present invention;

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that the embodiments of thetransmission of the present invention have an arrangement of permanentmechanical connections between the elements of the four planetary gearsets in common. These mechanical connections generically link or relatethe transmission embodiments. More specifically, a first component orelement of a first planetary gear set is permanently coupled to a firstcomponent or element of a second planetary gear set. A second componentor element of the first planetary gear set is permanently coupled to afirst component or element of a third planetary gear set. A thirdcomponent or element of the first planetary gear set is permanentlycoupled to a ground or a transmission housing. A second component orelement of the second planetary gear set is permanently coupled to asecond component or element of a third planetary gear set. A thirdcomponent or element of the third planetary gear set is permanentlycoupled to a first component or element of a fourth planetary gear set.

Referring now to FIG. 1, an embodiment of an eight speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear are each represented by a node. Therefore, a single lever containsthree nodes: one for the sun gear, one for the planet gear carrier, andone for the ring gear. The relative length between the nodes of eachlever can be used to represent the ring-to-sun ratio of each respectivegear set. These lever ratios, in turn, are used to vary the gear ratiosof the transmission in order to achieve an appropriate ratios and ratioprogression. Mechanical couplings or interconnections between the nodesof the various planetary gear sets are illustrated by thin, horizontallines and torque transmitting devices such as clutches and brakes arepresented as interleaved fingers. If the device is a brake, one set ofthe fingers is grounded. Further explanation of the format, purpose anduse of lever diagrams can be found in SAE Paper 810102, “The LeverAnalogy: A New Tool in Transmission Analysis” by Benford and Leisingwhich is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The first node 14A of the first planetary gear set 14 is coupled toground or the transmission housing 50. The second node 14B of the firstplanetary gear set 14 is coupled to the first node 18A of the thirdplanetary gear set 18. The third node 14C of the first planetary gearset 14 is coupled to second node 16B of the second planetary gear set16. The third node 16C of the second planetary gear set 16 is coupled tothird node 18C of the third planetary gear set 18. The second node 18Bof the third planetary gear set 18 is coupled to the first node 20A ofthe fourth planetary gear set 20. The third node 20C of the fourthplanetary gear set 20 is coupled to the input shaft or member 12. Theoutput shaft or member 22 is coupled to the second node 20B of thefourth planetary gear set 20.

A first clutch 26 selectively connects the input shaft or member 12 tothe first node 16A of the second planetary gear set 16. A second clutch28 selectively connects the first node 16A of the second planetary gearset 16 to the second node 20B of the fourth planetary gear set 20. Athird clutch 30 selectively connects the first node 16A of the secondplanetary gear set 16 to the second node 14B of the first planetary gearset 14. Fourth clutch 32 selectively connects third node 18C of thethird planetary gear set 18 to second node 20B of the fourth planetarygear set 20. A brake 34 selectively connects the first node 18A of thethird planetary gear set 18 to the ground or transmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the eight speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches, brake and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, planetary gear set 14 is a planetary gear set that includesa sun gear member 14A, a planet gear carrier member 14B and a ring gearmember 14C. Sun gear member 14A is connected to the ground ortransmission housing 50 through a first interconnecting shaft or member46. The planet gear carrier member 14B rotatably supports a set ofplanet gears 14D (only one shown) and is connected for common rotationwith first and second intermediate shafts or members 48 and 52. Planetgears 14D are each configured to intermesh with both sun gear member 14Aand ring gear member 14C. Ring gear member 14C is connected for commonrotation with a third intermediate shaft or member 54.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

Planetary gear set 16 is a planetary gear set that includes a sun gearmember 16C, a planet carrier member 16B that rotatably supports a set ofplanet gears 16D and a ring gear member 16A. Sun gear member 16C isconnected for common rotation with fourth and fifth intermediate shaftsor members 56 and 58. Planet carrier member 16B is connected for commonrotation with third intermediate shaft or member 54. Ring gear member16A is connected for common rotation with a sixth intermediate shaft ormember 60. Planet gears 16D are each configured to intermesh with bothsun gear member 16C and ring gear member 16A.

Planetary gear set 18 is a planetary gear set that includes a sun gearmember 18C, a ring gear member 18A and a planet carrier member 18B thatrotatably supports a set of planet gears 18D. Sun gear member 18C isconnected for common rotation with fifth intermediate shaft or member58. Ring gear member 18A is connected for common rotation with a seventhintermediate shaft or member 62. Planet carrier member 18B is connectedfor common rotation with an eighth intermediate shaft or member 64.Planet gears 18D are each configured to intermesh with both sun gearmember 18C and ring gear member 18A.

Planetary gear set 20 is a planetary gear set that includes a sun gearmember 20C, a ring gear member 20A and a planet carrier member 20B thatrotatably supports a set of planet gears 20D. Sun gear member 20C isconnected for common rotation with input shaft or member 12. Ring gearmember 20A is connected for common rotation with eighth intermediateshaft or member 64. Planet carrier member 20B is connected for commonrotation with output shaft or member 22 and ninth intermediate shaft ormember 66. Planet gears 20D are each configured to intermesh with bothsun gear member 20C and ring gear member 20A.

The torque-transmitting mechanisms or clutches 26, 28, 30, 32 and brake34 allow for selective interconnection of the shafts or interconnectingmembers, members of the planetary gear sets and the housing. Forexample, first clutch 26 is selectively engageable to connect inputshaft or member 12 to sixth intermediate shaft or member 60. Secondclutch 28 is selectively engageable to connect sixth intermediate shaftor member 60 to ninth intermediate shaft or member 66. Third clutch 30is selectively engageable to connect second intermediate shaft or member52 to sixth intermediate shaft or member 60. Fourth clutch 32 isselectively engageable to connect fourth intermediate shaft or member 56to sixth intermediate shaft or member 60. Brake 34 is selectivelyengageable to connect first and seventh intermediate shafts or member 48and 62 to transmission housing 50 to restrict rotation of shafts ormembers 48 and 62 relative to housing 50.

Referring now to FIGS. 2 and 3, the operation of the embodiment of theeight speed transmission 10 will be described. It will be appreciatedthat transmission 10 is capable of transmitting torque from the inputshaft or member 12 to the output shaft or member 22 in at least eightforward speed or torque ratios and at least one reverse speed or torqueratio. Each forward and reverse speed or torque ratio is attained byengagement of one or more of the torque-transmitting mechanisms (i.e.first clutch 26, second clutch 28, third clutch 30, fourth clutch 32 andbrake 34), as will be explained below. FIG. 3 is a truth tablepresenting the various combinations of torque-transmitting mechanismsthat are activated or engaged to achieve the various gear states. Actualnumerical gear ratios of the various gear states are also presentedalthough it should be appreciated that these numerical values areexemplary only and that they may be adjusted over significant ranges toaccommodate various applications and operational criteria of thetransmission 10. An example of the gear ratios that may be obtainedusing the embodiments of the present invention are also shown in FIG. 3.Of course, other gear ratios are achievable depending on the geardiameter, gear teeth count and gear configuration selected.

To establish reverse gear, first clutch 26 and brake 34, are engaged oractivated. First clutch 26 connects input shaft or member 12 to sixthintermediate shaft or member 60. Brake 34 connects first and seventhintermediate shafts or member 48 and 62 to transmission housing 50 torestrict rotation of shafts or members 48 and 62 relative to housing 50.Likewise, the eight forward ratios are achieved through differentcombinations of clutch engagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the eight speed transmission 10 assumes, first of all,that all the clutches and the brake not specifically referenced in agiven gear state are inactive or disengaged and, second of all, thatduring gear shifts, i.e., changes of gear state, between at leastadjacent gear states, a clutch or brake engaged or activated in bothgear states will remain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; a first interconnecting member continuouslyinterconnecting the first member of the first planetary gear set with astationary element; a second interconnecting member continuouslyinterconnecting the second member of the first planetary gear set withthe third member of the third planetary gear set; a thirdinterconnecting member continuously interconnecting the third member ofthe first planetary gear set with the second member of the secondplanetary gear set; a fourth interconnecting member continuouslyinterconnecting the first member of the second planetary gear set withthe first member of the third planetary gear set; a fifthinterconnecting member continuously interconnecting the second member ofthe third planetary gear set with the third member of the fourthplanetary gear set; and five torque transmitting mechanisms selectivelyengageable to interconnect one of the first, second, and third memberswith another of the first, second, third members, and the stationaryelement, and wherein the torque transmitting mechanisms are selectivelyengageable in combinations of at least two to establish at least eightforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 2. The transmission of claim 1wherein a first of the five torque transmitting mechanisms isselectively engageable to interconnect the second member of the firstplanetary gear set with the third member of the second planetary gearset.
 3. The transmission of claim 2 wherein a second of the five torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the first planetary gear set with the stationaryelement.
 4. The transmission of claim 3 wherein a third of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe third member of the second planetary gear set with at least one ofthe first member of the fourth planetary gear set and the input member.5. The transmission of claim 4 wherein a fourth of the five torquetransmitting mechanisms is selectively engageable to interconnect thethird member of the second planetary gear set with the second member ofthe fourth planetary gear set.
 6. The transmission of claim 5 wherein afifth of the five torque transmitting mechanisms is selectivelyengageable to interconnect at least one of the first member of thesecond planetary gear set and the first member of the third planetarygear set with the second member of the fourth planetary gear set.
 7. Thetransmission of claim 1 wherein the first members are sun gears, thesecond members are carrier members, and the third members are ringgears.
 8. The transmission of claim 1 wherein the input member iscontinuously interconnected with the first member of the fourthplanetary gear set and wherein the output member is continuouslyinterconnected with the second member of the fourth planetary gear set.9. The transmission of claim 1 wherein one of the torque transmittingmechanisms is a brake and four of the torque transmitting mechanisms areclutches.
 10. The transmission of claim 1 wherein the stationary elementis a transmission housing.
 11. A transmission comprising: an inputmember; an output member; first, second, third and fourth planetary gearsets each having first, second and third members, wherein the inputmember is continuously interconnected with the first member of thefourth planetary gear set and wherein the output member is continuouslyinterconnected with the second member of the fourth planetary gear set;a first interconnecting member continuously interconnecting the firstmember of the first planetary gear set with a stationary element; asecond interconnecting member continuously interconnecting the secondmember of the first planetary gear set with the third member of thethird planetary gear set; a third interconnecting member continuouslyinterconnecting the third member of the first planetary gear set withthe second member of the second planetary gear set; a fourthinterconnecting member continuously interconnecting the first member ofthe second planetary gear set with the first member of the thirdplanetary gear set; a fifth interconnecting member continuouslyinterconnecting the second member of the third planetary gear set withthe third member of the fourth planetary gear set; a first torquetransmitting mechanism selectively engageable to interconnect the secondmember of the first planetary gear set with the third member of thesecond planetary gear set; a second torque transmitting mechanismselectively engageable to interconnect the second member of the firstplanetary gear set with the stationary element; a third torquetransmitting mechanism selectively engageable to interconnect the thirdmember of the second planetary gear set with at least one of the firstmember of the fourth planetary gear set and the input member; a fourthtorque transmitting mechanism selectively engageable to interconnect thethird member of the second planetary gear set with the second member ofthe fourth planetary gear set; and a fifth torque transmitting mechanismselectively engageable to interconnect at least one of the first memberof the second planetary gear set and the first member of the thirdplanetary gear set with the second member of the fourth planetary gearset, and wherein the torque transmitting mechanisms are selectivelyengageable in combinations of at least two to establish at least eightforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 12. The transmission of claim 11wherein the first members are sun gears, the second members are carriermembers, and the third members are ring gears.
 13. The transmission ofclaim 11 wherein the stationary element is a transmission housing.
 14. Atransmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having a sun gear, acarrier member and a ring gear, wherein the input member is continuouslyinterconnected with the sun gear of the fourth planetary gear set andwherein the output member is continuously interconnected with thecarrier member of the fourth planetary gear set; a first interconnectingmember continuously interconnecting the sun gear of the first planetarygear set with a stationary element; a second interconnecting membercontinuously interconnecting the carrier member of the first planetarygear set with the ring gear of the third planetary gear set; a thirdinterconnecting member continuously interconnecting the ring gear of thefirst planetary gear set with the carrier member of the second planetarygear set; a fourth interconnecting member continuously interconnectingthe sun gear of the second planetary gear set with the sun gear of thethird planetary gear set; a fifth interconnecting member continuouslyinterconnecting the carrier member of the third planetary gear set withthe ring gear of the fourth planetary gear set; a first torquetransmitting mechanism selectively engageable to interconnect thecarrier member of the first planetary gear set with the ring gear of thesecond planetary gear set; a second torque transmitting mechanismselectively engageable to interconnect the carrier member of the firstplanetary gear set with the stationary element; a third torquetransmitting mechanism selectively engageable to interconnect the ringgear of the second planetary gear set with at least one of the sun gearof the fourth planetary gear set and the input member; a fourth torquetransmitting mechanism selectively engageable to interconnect the ringgear of the second planetary gear set with the carrier member of thefourth planetary gear set; and a fifth torque transmitting mechanismselectively engageable to interconnect at least one of the sun gear ofthe second planetary gear set and the sun gear of the third planetarygear set with the carrier member of the fourth planetary gear set, andwherein the torque transmitting mechanisms are selectively engageable incombinations of at least two to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 15. The transmission of claim 14 wherein thestationary element is a transmission housing.